Ho Y K
Res Commun Chem Pathol Pharmacol. 1979 Aug;25(2):293-306.
Partially thiolated polycytidylic acid (MPC), a representative member of the "antitemplate" class of novel chemotherapeutic agents, is a potent inhibitor of the E. coli DNA-dependent RNA polymerase. It inhibited 50% of the enzymic reaction at a concentration of 6 micrometers. Kinetic studies indicated that MPC had no effect on the chain elongation of the transcription process, but it appeared to inhibit the initiation of RNA synthtesis presumably by competing with the DNA template for binding to the RNA polymerase. Binding studies, using a gel filtration method, showed that MPC and the RNA polymerase formed a stable complex which was not dissociated by 0.3 M NaCl. It is inferred that mixed disulfide linkage(s) might have been formed between the enzyme and MPC. The implications of these findings are discussed.
部分硫醇化聚胞苷酸（MPC）是新型化疗药物“抗模板”类的代表性成员，是大肠杆菌DNA依赖性RNA聚合酶的有效抑制剂。它在浓度为6微摩尔时抑制了50%的酶促反应。动力学研究表明，MPC对转录过程的链延伸没有影响，但它似乎通过与DNA模板竞争结合RNA聚合酶来抑制RNA合成的起始。使用凝胶过滤法的结合研究表明，MPC和RNA聚合酶形成了一种稳定的复合物，该复合物不会被0.3M NaCl解离。据推测，酶和MPC之间可能形成了混合二硫键。讨论了这些发现的意义。
